College football: "Defense is controlled insanity," safety Shaun Williams says. "You have to be . . . able to see things in a split second and react."

Rocky Long, the defensive coordinator, waves his hands and flaps his arms, then holds his head, all of which means either UCLA should line up a certain way or somebody should turn out the lights and watch the bunny on the wall.

Safety Shaun Williams relays the call in a more laid-back way to the cornerback near the opposite sideline from the Bruin bench.

The other team breaks the huddle, and linebacker Brian Willmer lets everybody know where the tight end is because that's the offense's strength.

Then Williams' mental wheels really start turning:

--Echo Willmer's call or dispute it?

--How many wide receivers are in and where are they lined up? (That usually gives the passing strength, often--but not always--away from the tight end.)

--How far are they split from the rest of the formation? (That sometimes tips a pass route.)

--How many backs are in, and where are they lined up?

--Is the weight of the linemen forward? (It's probably a run.) Or backward? (Probably a pass.)

Each decision is relayed to the rest of the Bruin defensive backs, who adjust their techniques accordingly.

At the same time, Williams is moving, coming to the line or backing away, moving left or right, the defensive quarterback being watched by the offensive quarterback, who waits for him to tip off a weakness in the UCLA defense:

--Is Williams blitzing? (Look for a receiver to run where the defensive back used to be.)

--Or is he backing off in coverage? (Perhaps there is an extra second to look for another receiver.)

It's a mental chess match, run 75-85 times a game.

And then Williams gets to hit somebody.

"That's just like your little dessert," he says, laughing. "From all that hard mental work, you get to hit somebody. That's the reward for doing all these things to put yourself in position to make plays."

He has had enough dessert to weigh twice his 205 pounds.

He is fourth on the Bruin list of tacklers, with 43, behind only the three linebackers: Willmer, Danjuan Magee and Phillip Ward. Williams has rushed enough to make three sacks and has dropped back enough to knock down 10 passes and get one interception in seven games.

"His position is probably the most difficult position on the defense, according to Rocky," Coach Bob Toledo said. "He's got to cover a back, he's got to cover a wide receiver, he's got to cover a tight end, he's got to blitz, he's got to be like a linebacker. It takes a special football player to play the position. . . . He's a guy that's got to be all over the field. That's why I say he's the glue that holds it together."

And when there's no glue, it falls apart.

Williams sat out the California and Stanford games because of a knee injury, and UCLA needed a big lead at Berkeley to hold on for a victory. The Bruins blew a lead in losing to Stanford, which completed seven passes in its final scoring drive.

"I tell you what, there is no doubt in my mind that if Shaun had been there [against Stanford], we would have won the football game. That's how big he is for us," Toledo said.

Williams, a junior, returned against Washington State on Saturday with six tackles, one of them a sack that forced a punt, which the Bruins blocked. UCLA won, 38-14.

He's a defensive back by choice, after becoming a running back at UCLA by accident.

Williams was recruited as what Bruin coaches call "athlete," an undefined position that mainly involves getting to Westwood and sorting things out.

He had played both at Crespi High in the San Fernando Valley, seldom coming off the field, and when he got to UCLA it seemed defensive back was the path of least resistance to playing time.

That changed in his second week of practice in 1994, when Karim Abdul-Jabbar and Skip Hicks were nursing knee problems. Suddenly, Williams was a running back.

And Abdul-Jabbar, and then Hicks, got well, and Williams was again a defensive back, after running the ball four times for five yards.

Both coordinators--then Toledo for the offense and Bob Field for the defense--wanted him.

"Terry [Donahue, then the head coach] made an executive decision," said Field, who now works with the safeties under Long. "That's all it was."

It seems so long ago. Toledo remembers Williams carrying the ball against Washington State. The UCLA media guide says it was against Brigham Young. Actually, it was against Southern Methodist in the second game of the season, but four weeks later, Williams was starting at free safety against California.

He was back at home.

"I was just looking to play," he said. "I was thrilled to be on the field, and I was confident I could play on either side of the ball.

"I'd love to get in there and touch the ball a couple of times on offense, but I really want to master my game on defense, to play the perfect game: not making any mental mistakes, not making any alignment errors, not missing any tackles and making plays when I have an opportunity to make plays.